add Haskell snippet to find files in a directory by extension

Author: ACR1209

snippets/haskell/file-handling/find-files-with-extension-in-directory.md

@@ -0,0 +1,23 @@
+---
+title: Find Files in Directory by Type
+description: Finds all files in a directory with a specific extension.
+author: ACR1209
+tags: haskell,file,search,extension,filesystem
+---
+
+```hs
+import System.Directory (listDirectory)
+import System.FilePath (takeExtension)
+
+findFilesByExtension :: FilePath -> String -> IO [FilePath]
+findFilesByExtension dir ext = do
+    files <- listDirectory dir
+    return $ filter (\f -> takeExtension f == ext) files
+
+main :: IO ()
+main = do
+    let directory = "."
+    let ext = ".txt"
+    files <- findFilesByExtension directory ext
+    mapM_ putStrLn files -- Output: list of txt files on the current directory
+```